Apparatus for heat-treating textiles



Aug. 19,1969 J.RASCHLE 3,461,519

APPARATUS FOR HEAT-TREATING TEXTILES Filed Jan. 5, 1967 J. E. INVENTOR.

woser #650,445

fro A 5/6 United States Patent US. Cl. 28-62 11 Claims ABSTRACT OF THE DISCLOSURE This invention relates to apparatus for use in the heat treatment of textiles, typically to form textured textile materials, and to the process for using the same. The apparatus comprises a heat-transfer member having a relatively thin coating of a heat-resistant polymeric material having a low surface energy. Fillers may be incorporated into the polymeric coating. The apparatus may have a grooved surface, adapted to receive textile yarns.

This invention relates to novel apparatus for heat-treating textile yarns.

Processes and apparatuses for texturing textile yarns consisting at least partly of thermoplastic material are known according to which the heated yarn is subjected to temporary high twist, e.g., false twist, or is passed through a stuffing box or over a sharp edge, The yarn is thereby temporarily made to pass into a plastic condition, after which rehardening of the thermoplastic fiber material is effected by cooling. In various known false-twist devices for texturing yarns, the heating of this highly twisted yarn is effected by means of heated contact surfaces, e.g., metal rails or plates. Other devices of this kind are known in which heatable contact plates are provided to post-heat back-twisted yarns. Furthermore, false-twist devices are known in which the yarns are passed in the axial direction through metal tubes which are heated by means of an electrical heating coil, the heat-setting being effected by convection. In all these cases, when the yarns are heated, the sizing agents and other compositions with which the yarns have previously been treated evaporate and the vapours formed condense at least in part and are deposited on the heat transfer surfaces. These solid or crystalline deposits are highly adherent to the heat-transfer surfaces and cause a change in the heat-transfer properties of the heating'surface. In the case of contact surfaces, soiling of the yarn also results. Eliminating the deposits by means of scrapers is disadvantageous in that it is time-consuming and causes damage to the heat-transfer surfaces, Similar difiiculties are encountered where texturing is effected in a stuffing box since solid or crystalline deposits form on the interior face of the walls of the stuffing box which also serve as the heat-transfer surfaces. These deposits not only reduce the efliciency of heat-transfer, but also hinder the movement of the yarns in the stuflingbox and thereby cause irregularities in the texture effect.

It is an object of this invention to provide novel improved aparatus for heat-treating textiles. Other objects will be apparent to those skilled in the art from the following description.

The apparatus of this invention comprises a heat-transfer member having a surface through which heat is transferred to a yarn, said surface bearing a thin coating of a polymeric material which is resistant to temperatures of at least about 200 C. and which has a low surface energy.

The heat-transfer member will preferably be a flat or tube-shaped member which is capable of being heated. It

will suitably be constructed of a material having high heat conductivity, e.g., a metal, and preferably a metal such as aluminum.

The formation of adherent deposits on the surface of said member is avoided by providing a coating of a material on which deposits will not form at all or from which the deposits are easily removed. In accordance with this invention, the coating will be a thin film of a polymeric material characterized by low surface energy and ability to withstand temperatures of the order of about 200 C. to about 300 C. The preferred polymeric materials are fiuoropolymers, i.e., the homopolymers and copolymers of tetrafiuoroethylene, hexafiuoropropylene, trifluoroethylene, etc. For example, the preferred polymeric materials include polytetrafiuoroethylene; copolymers of tetrafluoroethylene and hexafluoropropylene; polytrifluoroethylene; etc. In addition to the preferred materials, there may be used such polymeric materials as polyphenylene oxide, poly-para-xylylene, polyimides, epoxide resins and silicone resins which have the desired degree of heat-resistance, The epoxide resins coatings are generally prepared from an epoxide formed by reacting epichlorohydrin with a polyhydric material, typically a polyol such as bisphenol- A. The coating is formed by extending and crosslinking the epoxide with a diamine, diacid, polyamide, urea-formaldehyde or phenolic resin. Silicone resin coatings are typically alkyl or aryl polysiloxanes, preferably co-condensation products prepared from mixtures of alkyl, say methyl, and aryl, say phenyl, halosilanes and containing predominantly dihalosilanes with small amounts of trihalosilane as a cross-linking site.

It is frequently advantageous to incorporate in the coating, as a filler, powdered or flake metal or mineral particles, such as silica, aluminum oxide and aluminum. These fillers are useful in improving the temperature resistance of the coatings by enhancing their ability to dissipate heat. Fluoropolymers treated with aluminum oxide are especially useful. The coatings employed are typically in the form of thin films, generally having a thickness of between about 20x10" and 60x10 meters m).

The application of the coating to the surface of the heat transfer member will be by a technique suitable for the particular polymeric material. For example, the coating may be applied in a finely powdered state to an etched or sand-blasted surface and thereafter fused by heating. It may be applied as an uncured liquid and thereafter cured. Alternatively, a preformed film may be prepared which may be wrapped around, fused or adhesively secured to the surface. The coating may be applied to the whole surface of the heat transfer member or only to portions of the surface along which the yarns are guided. For instance the coated portions may be grooves adapted to receive the yarns.

Illustrative embodiments of the invention are shown in the drawings attached hereto. FIGS. 1, 2, 3 and 4 illustrate typical plate-shaped members of the invention and FIGS. 5, 6, 7 and 8 illustrate tubular members. FIG. 1 is a cross-sectional view of a vaulted metal, preferably aluminum, plate-shaped heat-transfer member 10 having a plurality of grooves 11 adapted to receive the yarn to be treated (not shown), said grooves bearing a coating of polytetrafluoroethylene 12 of approximately 40x10- meters thickness. Member 10 is also provided with an internal heating coil (not shown).

FIG. 2 is a cross-sectional view of a similar vaulted metal, plate-shaped member 20 having a single yarn-receiving groove 21 bearing a coating of polytetrafluoroethylene 22 of approximately 40 1O- meters and having an internal heating coil (not shown).

FIG. 3 is a cross-sectional view of a metal, plate-shaped, heat-transfer member 30 having a flat surface 31 for contact with the yarn to be treated (not shown), said flat surface bearing a coating of polytetrafluoroethylene 32 of approximately 40 10- meters thickness. Member 30 is also provided with an internal heating coil (not shown).

FIG. 4 is a top-view of a plate-shaped heat-transfer member 40 of the type shown in FIG. 2, having a single groove 41 adapted to receive a yarn (not shown), said groove having a surface coating of polytetrafluoroethylene 42 of approximately 40 60 meters thickness.

FIG. 5 is a cross-sectional view of bent tubular aluminum heat-transfer member 50 adapted for the passage therethrough of a yarn (not shown). The interior surface of member 50 is coated with a film of polytetrafiuoroethylene 51 of approximately 35 l0 meters thickness. Member 50 is provided with means for heating (not shown) the interior surface thereof as by connecting it as a resistance element in an electrical circuit. Yarn (not shown) passing through member 50 is heated by conve tion and by contact with coating 51.

FIG. 6 is a top view of tubular heat-transfer member 60, this being the same member as that shown in FIG. 5.

FIG. 7 is a cross-sectional view of straight tubular aluminum heat-transfer member 70 having a coating of polytetrafluoroethylene 71 of approximately 35 10 meters thickness on the interior surface thereof and provided with longitudinal slot 72 to allow introduction of yarn (not shown) therein. Member 70 is provided with means for heating (not shown) the interior surface thereof in a manner similar to that of the member of FIG. 5. Yarn (not shown) passing through member 70 may, as desired, be heated solely by convection by conducting said yarn along the longitudinal axis of said member, or it may be allowed to contact coating 71.

FIG. 8 is a top view of member 80, this being the same member as that shown in FIG. 7.

In all of the embodiments illustrated, any deposits which form are present in a relatively non-adherent state and are readily stripped from the coating of polymeric material. It will be understood that reference has been made to specific embodiment of the invention solely for the purpose of illustration and the instant invention encompasses all such variation and modifications thereof as fall within its general scope.

What is claimed is:

1. Apparatus for use in the heat treatment of textile yarns comprising a heat transfer member having a surface through which heat is transferred to the yarn and a film coating of a polymeric material having incorporated there- & in a filler selected from the group consisting of metal and mineral particles, said coating having a low surface energy and being resistant to temperatures of the order of 200 to 300 C.

2. Apparatus according to claim 1, wherein said polymeric material is a fluoropolymer.

3. Apparatus according to claim 2, wherein said polymeric material is polytetrafiuoroethylene.

4. Apparatus according to claim 2 wherein said filler is aluminum oxide.

5. Apparatus according to claim 1, wherein said polymeric material is a silicone resin.

6. Apparatus according to claim 1, meric material is an epoxide resin.

7. Apparatus according to claim '1, wherein said polymeric material is polyimide.

8. Apparatus according to claim 1, wherein said polymeric material is polyphenylene oxide.

9. Apparatus according to claim 1, meric material is poly-para-xylylene.

10. Apparatus according to claim 1, wherein the film of polymeric material is of the order of between about 20 10- and 10 meters in thickness.

11. Apparatus for use in the heat treatment of textile yarns comprising: a heat transfer member through which heat is transferred to the yarn, said surface being formed with at least one groove through which the yarn to be treated may be guided, and a film coating of a polymeric material having incorporated therein a filler selected from the group consisting of metal and mineral particles on the grooved portion of said surface, said coating having a low surface energy and being resistant to temperatures of the order of 200 to 300 C.

wherein said polywherein said poly- References Cited UNITED STATES PATENTS 2,789,926 4/1957 Finholt et a1 117213 2,809,130 10/1957 Rappaport 117-1388 2,831,313 4/1958 Burns et al.

2,949,659 8/1960 Heijnis et al.

3,292,231 12/1966 Epstein.

2,811,471 10/1957 Homeyer.

3,071,838 1/1963 Scragg 28-62 3,289,400 12/1966 Scragg 2862 X LOUIS K. RIMRODT, Primary Examiner 

